1. Field of the Invention
The invention relates to a microwave oven for cooking foodstuffs, and more particularly to a microwave oven provided with a rotatable tray on which foodstuffs are mounted.
2. Description of Prior Art
In a conventional microwave oven, such as an electronic oven range, articles on a cooking tray inside the cooking chamber of an oven are heated by microwaves, which are radiated directly from a microwave generator, such as a magnetron, and/or radiated indirectly inside the cooking chamber with a relatively larger amount of microwaves.
Also, some of conventional microwave ovens have been provided with a rotatable tray in order to get articles thereon to be heated equally by directly and indirectly radiating microwaves.
Japanese Utility Model Laid-Open Publication No. Sho. 61-19999, published on Feb. 5, 1986 has disclosed a representative example of a conventional electronic oven range including a rotatable tray. The oven range disclosed in the above Japanese application comprises a rotatable tray, a driving motor having a driving shaft driving the rotatable tray, a rotatable driven arm assembly mounted detachably to the driving shaft of a motor in the base under the rotatable tray. A plurality of rotatable support rollers are respectively mounted to some of the arms at a predetermined interval, and a guide groove is formed under the rotatable tray for receiving the support rollers therein thereby to force the rollers to move frictionally and slidably thereon. Also provided are sub-rollers of the same quantity as the support rollers, in which each of sub-rollers has a diameter smaller than that of the support roller. The sub-rollers are mounted detachably to the remaining rotatable driven arms so that each sub-roller is positioned between two of the support rollers.
Also, there has been another example of the conventional electronic oven range, as disclosed in Japanese Utility Model Laid-Open Publication No. Sho. 60-118894, published on Aug. 10, 1985. This Japanese application has disclosed an electronic oven range comprising a rotatable tray, a plurality of support rollers mounted under the rotatable tray in order to support the tray while slidably moving around the rotating center of the rotatable tray. A roller support for the support rollers induces the rollers to move the rotatable tray in radial direction. A microwave reflector moves along with the rollers at radial directions, and a roller path is provided for guiding the movement of the rollers, the path being non-concentric to the rotation center of the rotatable tray.
However, in a conventional microwave oven, such as the electronic oven range disclosed in the Japanese applications, the tray has been provided with a horizontal flat surface and simply positioned on the rotation member of the oven. Therefore, during operation, the incidence angles of microwaves radiating toward articles on the rotatable tray are always fixed. Thus, the microwave radiation to the articles could not be uniformly dispersed, thereby causing the cooking performance of an electronic oven range to be deteriorated.
Accordingly, if microwaves radiate at various incidence angles to the surface of articles on a rotatable tray, a microwave oven, such as a cooking oven, can remarkably enhance the reliability of products.
Also, it is noted that the variation of the incidence angles can accomplish the uniform radiation of microwaves to articles to be cooked.
Thus, it is an object of the invention to provide a microwave oven for performing the operation of a rotation member in various methods to induce the uniform radiation of microwaves to articles to be cooked.
It is other object of the invention to provide a microwave oven capable of varying incidence angles of microwaves radiating to articles on a rotatably tray.
It is another object of the present invention to provide a microwave oven capable of rotating a rotation member following its up/down movement according to the rising and lowering of the rotation member.
It is still another object of the invention to provide a microwave oven including a rotation member, a plurality of arms which are partly raised in a paired form when other arms are lowered in a paired form, or vice versa.
In accordance with the invention, the above and other objects can be accomplished by providing three embodiments embodying a microwave oven according to the invention.